Low molecular weight polystyrene resin and methods of making and using the same

ABSTRACT

A low z-average molecular weight, high softening point polystyrene resin having a narrow molecular weight distribution, as well as methods of making and using the same, are provided. The use of an inert solvent and/or the order of addition of reactants during polymerization may contribute to the unique properties of the final homopolymeric resin. The polystyrene resin can be partially or fully hydrogenated and may have particular use as a tackifying agent in a variety of hot melt adhesive and rubber compositions.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/587,681 filed on Jan. 18, 2012, the disclosures of which areincorporated herein by reference to the extent they do not contradictthe statements herein.

FIELD OF THE INVENTION

This invention relates to processes and systems for making low molecularweight polystyrene resins. In another aspect, this invention relates tothe use of such resins, particularly as components of adhesivecompositions.

BACKGROUND

Hydrocarbon resins are widely useful in a variety of applications,including as modifiers in polymeric systems, or as additives inadhesives, rubber, hot melt coatings, printing inks, flooring materials,and other systems. In many applications, selection of a hydrocarbonresin having specific properties may be important in order to ensurecompatibility of the resin with the other components and/or in order toproduce a polymeric system having a desired thermal stability, range ofmechanical properties, and/or degree of processability. For example, insome applications, resins having a high softening point with narrowmolecular weight distribution may be required. In the past, this type ofresin was often produced via copolymerization of a plurality ofpetroleum compounds, such as those components of cracked petroleumdistillate, turpentine fractions from natural product distillation, coaltar C10 olefins, and/or pure aromatic monomers resulting fromFriedel-Crafts reactions of aromatic compounds. Styrene is a lessexpensive and more available pure monomer. It is, however, difficult toproduce a homopolymer of styrene having a desired high softening pointwith reasonably low z-average molecular weight and narrowpolydispersity.

Thus, a need exists for a hydrocarbon-based resin having a narrowmolecular weight distribution, a low z-average molecular weight, and ahigh softening point. The resin should be widely applicable and usefulin a number of end use applications, including, for example, as atackifier in adhesive compositions.

SUMMARY

One embodiment of the present invention concerns a process for producinga styrenic resin comprising: (a) combining at least a solid acidcatalyst, an inert solvent, and styrene to thereby form a reactionmixture; and (b) polymerizing at least a portion of the styrene in thereaction mixture to thereby produce a polystyrene polymer having a Ring& Ball softening point of at least 70° C. and a z-average molecularweight (Mz) of not more than 4,000 dalton, wherein the inert solvent hasan aromatic hydrogen content of not more than 10 percent, as measured byproton NMR.

Another embodiment of the present invention concerns a process forproducing a styrenic resin comprising: (a) combining at least a solidacid catalyst, a solvent, and one or more monomers to thereby form areaction mixture, wherein styrene makes up at least 95 weight percent ofthe one or more monomers; and (b) polymerizing at least a portion of thestyrene in the reaction mixture to thereby provide a polystyrene polymerhaving Ring & Ball softening point of at least 70° C. and apolydispersity index of not more than 2.0.

Yet another embodiment of the present invention concerns a styrenicresin comprising not more than 5 weight percent of moieties other thanstyrenic moieties, the styrenic resin having a Ring & Ball softeningpoint of at least 70° C., a z-average molecular weight (Mz) of not morethan 3,500 dalton, and a polydispersity index of not more than 2.0.

Still another embodiment of the present invention concerns an adhesivecomposition comprising: (a) at least 15 weight percent and not more than85 weight percent of one or more adhesive base polymers; (b) at least 5weight percent and not more than 75 weight percent of a tackifier; (c)not more than 35 weight percent of an oil; (d) not more than 40 weightpercent of one or more waxes; and (e) not more than 10 weight percent ofone or more additional components, wherein the tackifier comprises astyrenic resin having a Ring & Ball softening point of at least 70° C.and not more than 125° C., a z-average molecular weight (Mz) of not morethan 4,000 dalton, and a polydispersity index of not more than 2.0,wherein the styrenic resin is an at least partially hydrogenatedpolystyrene resin comprising not more than 5 weight percent of moietiesother than styrenic moieties.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic representation of a polystyrene productionfacility configured according to one embodiment of the present inventionoperable to produce a polystyrene resin as described herein;

FIG. 2 is a graphical summary of the results of a dynamic mechanicalanalysis of several comparative and inventive nonwoven adhesives,particularly illustrating the low application temperature and desirableadhesive properties of nonwoven adhesives formulated according toembodiments of the present invention;

FIG. 3 is a graphical summary of the results of a dynamic mechanicalanalysis of several comparative and inventive packaging adhesives,particularly illustrating the low application temperature and desirableadhesive properties of packaging adhesives formulated according toembodiments of the present invention;

FIG. 4 is a graphical summary of initial (formulation) and final (aged)rheological curves for several comparative and inventive nonwovenadhesives, particularly illustrating the greater thermal stability ofnonwoven adhesives formulated according to embodiments of the presentinvention;

FIG. 5 is a graphical summary of initial (formulation) and final (aged)rheological curves for several comparative and inventive packagingadhesives, particularly illustrating the greater thermal stability ofthe packaging adhesives formulated according to embodiments of thepresent invention; and

FIG. 6 summarizes the results of SAFT performed on several comparativeand inventive packaging adhesive compositions, particularly illustratingthe at least comparable performance of packaging adhesives formulatedaccording to embodiments of the present invention.

DETAILED DESCRIPTION

Processes and systems for producing low z-average molecular weight, highsoftening point styrenic resins according to embodiments of the presentinvention are provided. As used herein, the term “styrenic resin”broadly refers to an unhydrogenated or at least partially (i.e.,partially or fully) hydrogenated polystyrene resin. One or moreinventive styrenic resins can be particularly suitable for a variety ofend use applications, including, for example, use as a tackifying resinin several types of adhesive or rubber compositions. Details regardingthe inventive styrenic resins, as well as methods of making and usingthe same, will now be discussed in detail, with general reference to theFigures.

Referring initially to FIG. 1, a schematic representation of apolystyrene production facility 10 configured according to oneembodiment of the present invention is provided. As shown in FIG. 1, amonomer feed stream in conduit 110 and a catalyst-containing feed streamin conduit 112 can be combined with a solvent in a polymerizationreactor 12. The resulting resin can then optionally be at leastpartially, or fully, hydrogenated in a hydrogenation zone 16. One ormore styrenic resins produced according to various embodiments describedherein can have a z-average molecular weight (Mz) of not more than about4,000 dalton, not more than about 3,500 dalton, not more than about3,000 dalton, not more than about 2,500 dalton, not more than about2,300 dalton, or not more than about 2,200 dalton, can also exhibit anunexpectedly high Ring & Ball softening point (ASTM E-28) of at leastabout 70° C., at least about 80° C., at least about 85° C., or at leastabout 90° C. Additional characteristics of the inventive styrenicresins, as well as uses thereof, will be discussed in detail shortly.

According to one embodiment of the present invention, the monomer feedstream in conduit 110 can comprise one or more pure monomers. As usedherein, the term “pure monomer” refers to one or more highly-purifiedmonomeric species. In contrast, monomer species such as “C5 monomers” or“C9 monomers” comprise mixtures of multiple monomeric species, typicallyderived from cracked petroleum or turpentine fractions, which includelow concentrations of a plurality of different types of monomers, eachhaving similar boiling ranges and/or molecular weights. Examples ofsuitable pure monomers can include, but are not limited to, styrene,alpha-methylstyrene (AMS), vinyltoluene, para-methylstyrene,beta-methylstyrene, and combinations thereof. In some embodiments, thepure monomer can be a styrene-based pure monomer and can comprisestyrene in an amount of at least about 90 weight percent, at least about95 weight percent, at least about 98 weight percent, at least about 99weight percent, or substantially all of the monomer introduced intoreactor 12. Consequently, in some embodiments, the polystyrene polymeror styrenic resin can be a polystyrene homopolymer comprising not morethan about 5 weight percent, not more than or less than about 2 weightpercent, not more than about 1 weight percent, or not more than about0.5 weight percent of moieties other than styrenic moieties. As usedherein, the term “styrenic moieties” refers to one or more moietiesderived from styrene and can include unhydrogenated or at leastpartially hydrogenated moieties of styrene. In other embodiments, two ormore of the above-listed pure monomers may be co-polymerized inpolymerization reactor 12 to thereby provide a polystyrene copolymercomprising at least about 5 weight percent, at least about 10 weightpercent, or at least about 15 weight percent of one or more non-styrenicmoieties.

The catalyst-containing feed stream in conduit 112 can comprise anysuitable type of solid polymerization catalyst. According to oneembodiment of the present invention, the solid polymerization catalystcan comprise a metal oxide solid acid catalyst having an acidity greaterthan about −3 on the Hammett scale. Examples of suitable metal oxidesolid acid catalysts are described in U.S. Pat. Nos. 6,133,386 and6,310,154, the entireties of which are incorporated herein by referenceto the extent not inconsistent with the present disclosure. As usedherein, the term “solid acid” refers to any solid which changes thecolor of a basic Hammett indicator with a pKl_(a)<0. Examples ofsuitable solid acid catalysts can include, but are not limited to, acidactivated clays, silica-alumina, amorphous silica-alumina, Bronsted acidon silica, Bronsted acid on silica-alumina, zeolites, mesoporoussilica-alumina, Bronsted acid on mesoporous silica, Bronsted acid onmesoporous silica-alumina, and combinations thereof.

In one embodiment, the acid activated clays may include naturallyoccurring clay minerals such as kaolinite, bentonite, attapulgite,montmorillonite, clarit, Fuller's earth, hectorite, or beidellite. Themontmorillonite can be treated with at least one member selected fromthe group consisting of sulfuric acid and hydrochloric acid. The acidactivated clay may also include synthetic clay. The synthetic clay mayinclude at least one member selected from the group consisting ofsaponite and hydrotalcite. The acid activated clay may include modifiedclay such as pillared clay. The pillared clay may include at least onemember selected from the group consisting of aluminum oxide pillaredclay, cerium modified alumina pillared clay, and metal oxide pillaredclay. The acid activated clay may include Bronsted acid on clay, whereinthe Bronsted acid includes at least one member selected from the groupconsisting of hydrofluoric acid, sulfuinc acid, nitric acid, phosphoricacid, and hydrochloric acid. One example of a commercially availablesolid acid clay catalyst suitable for use in embodiments of the presentinvention is FILTROL F-22 acid clay catalyst (commercially availablefrom BASF, Iselin, N.J.).

In one embodiment, the solid acid clay catalyst can be treated prior touse in polymerization reactor 12 to remove bound and/orfreely-associated water, thereby maximizing catalyst acidity andactivity. In one embodiment, the moisture content of the solid acid claycatalyst in conduit 112 can be at least about 1 weight percent, at leastabout 2 weight percent, or at least about 4 weight percent and/or notmore than about 10 weight percent, not more than about 8 weight percent,or not more than about 7 weight percent, based on the total weight ofthe solid acid clay catalyst in reactor 12. Similarly, the free watercontent in the monomer feed stream in conduit 110 can be limited to notmore than about 500 ppm, not more than about 200 ppm, not more thanabout 100 ppm, or not more than about 50 ppm, by volume, based on thetotal volume of the feed stream.

In some embodiments, the monomer feed stream in conduit 110 and/or thecatalyst-containing feed stream in conduit 112 can be optionallycombined with one or more polymerization solvents prior to, or shortlyafter, being introduced into reactor 12. When present, the amount ofsolvent in each stream can be at least about 10 weight percent, at leastabout 20 weight percent, at least about 35 weight percent and/or notmore than about 50 weight percent, not more than about 40 weightpercent, or not more than about 30 weight percent, based on the totalweight of the stream. The solvent can be any suitable type ofpolymerization solvent and can include recycled solvent, fresh solvent,or combinations thereof.

In one embodiment, the polymerization solvent can comprise a reactivesolvent. As used herein, the terms “reactive solvent” and “reactivepolymerization solvent” refer to a solvent that participates in thepolymerization reaction. Many reactive solvents have an aromatichydrogen content exceeding 20 percent. As used herein, the term“aromatic hydrogen content” refers to the ratio of the integration areaof aromatic hydrogen to the total hydrogen integration area, asdetermined by the proton NMR procedure described herein in Example 2.Examples of suitable reactive polymerization solvents can include, butare not limited to, benzene, alkyl-substituted benzenes such as xyleneand toluene, and light aromatic petroleum distillates such as “AromaticA-100” (commercially available from Exxon Mobil Chemical Company),“HiSol 10” (commercially available from Ashland Chemical Inc.), and“Cyclosol 53” (commercially available from Shell Chemical Company).

In another embodiment of the present invention, the polymerizationsolvent can comprise an inert solvent. As used herein, the terms “inertsolvent” and “inert polymerization solvent” refer to a solvent that doesnot significantly participate in the polymerization reaction. In someembodiments, an inert solvent may have a straight aniline point (ASTMD611-07) of at least about 40° C., at least about 45° C., or at leastabout 50° C. Although not wishing to be bound by theory, it ishypothesized that, unlike many reactive solvents, the molecularstructures of inert solvents may not alkylate the growing polymer chain.Accordingly, it has been unexpectedly discovered that resins polymerizedin inert solvents can exhibit a higher-than-expected softening point fora given polymerization temperature as compared to similar resinspolymerized in reactive solvents, as further illustrated shortly inExample 1.

Inert solvents can comprise one or more aliphatic hydrocarbon compounds,including, for example, straight-chain aliphatic hydrocarbons such ashexanes, heptanes, octanes, and isomers thereof; cycloaliphatichydrocarbons including cyclohexanes such tetramethylcyclohexane andtrimethylcyclohexane, and isomers thereof; halogen-substitutedhydrocarbon compounds, such as methylene chloride; and non-aromaticdistillate blends. In some embodiments, an inert solvent may alsoinclude a small amount of one or more reactive aromatic hydrocarboncompounds, while still maintaining its non-reactive functionality. Forexample, in some embodiments, the inert solvent can have an aromatichydrogen content of not more than about 10 percent, not more than about7 percent, not more than about 5 percent, not more than about 2 percent,or not more than about 1 percent, as determined by proton NMR procedureas described herein in Example 2. Examples of suitable inert solvents,can include, but are not limited to, mineral spirits such as whitespirits, Stoddard solvent, odorless mineral spirits, Rule 66 mineralspirits, Recycled Hydrogenation Solvent (commercially available fromEastman Chemical Company), and combinations thereof.

The monomer and catalyst-containing feed streams in conduits 110 and 112can be introduced into reactor 12 in any suitable order. In oneembodiment, the catalyst or a pre-mixed catalyst/solvent slurry can beintroduced into reactor 12, after it has been initially charged withmonomer. This addition of catalyst or a catalyst/solvent slurry to themonomer is referred to as “straight addition.” In another embodiment,the monomer feed stream in conduit 110 can be added, eitherincrementally or continuously, to a pre-mixed catalyst/solvent slurry ora fixed bed of pelletized catalyst initially charged or loaded into topolymerization reactor 12. The addition of the monomer to the catalystor catalyst/solvent slurry can also be referred to as “reverseaddition.” In some embodiments, the monomer and catalyst-containing feedstreams in conduits 110 and 112 can be introduced into polymerizationreactor 12 at substantially the same time, (not shown in FIG. 1).

Regardless of the specific reaction sequence employed to combine thecatalyst, solvent, and monomer, the resulting reaction mixture inpolymerization reactor 12 can have a catalyst loading of at least about1 weight percent, at least about 1.5 weight percent, at least about 2weight percent and/or not more than about 10 weight percent, not morethan about 7 weight percent, not more than about 5 weight percent, notmore than about 4 weight percent, or not more than about 3 weightpercent, based on the total weight of monomer introduced into reactor12. In addition, the combined reaction mixture can have asolvent-to-monomer (or styrene-to-monomer) weight ratio of at leastabout 30:70, at least about 40:60, or at least 45:55 and/or not morethan about 60:40, not more than about 50:50, or not more than about40:60 during polymerization of the monomer feed. In some embodiments,the combined reaction mixture in polymerization reactor 12 can alsoinclude one or more optional components, such as, for example chaintransfer agents (or compounds which behave as chain transfer agents).Examples of chain transfer agents and related compounds can include, butare not limited to, isobutylene, 2-methyl-1-butene, 2-methyl-2-butene,dimers or oligomers thereof, and combinations thereof. When present,these additional components can comprise not more than about 10 percent,not more than about 7 percent, not more than about 5 percent, or notmore than about 2 percent by weight of the total the combined reactionmixture.

During polymerization, the average temperature of the reaction mediumwithin reactor 12 can be at least about 0° C., at least about 35° C., atleast about 40° C., at least about 45° C., at least about 50° C., atleast about 55° C., at least about 60° C., at least about 65° C. and/ornot more than about 110° C., not more than about 105° C., not more thanabout 100° C., not more than about 95° C., not more than about 90° C.,not more than about 85° C., or not more than about 80° C. In someembodiments, polymerization reactor 12 can be operated substantiallyisothermally, such that the average reaction temperature changes by notmore than about 5° C. or not more than about 2° C. during the durationof the reaction. Any suitable system for controlling the reactiontemperature within reactor 12 can be used, including, for example, anexternal heat exchanger loop, one or more internal cooling coils, and/ora reactor cooling jacket.

The polymerization reaction can be carried out for a sufficient amountof time in order to achieve a desired polystyrene yield. According toone embodiment, the residence time, or reaction time at reactiontemperature, can be at least about 30 minutes, at least about 45minutes, or at least about 1 hour and/or not more than about 8 hours,not more than about 6 hours, or not more than about 4 hours. As aresult, the polystyrene yield can be at least about 10 percent, at leastabout 25 percent, at least about 50 percent, at least about 75 percent,at least about 85 percent, at least about 90 percent, or at least about95 percent, based on the total monomer fed to reactor 12. Thepolymerization reaction can be carried out in a continuous, batch, orsemi-batch mode and reactor 12 can comprise any suitable type ofreactor, including, for example, a fixed bed reactor, a fluidized bedreactor, a continuous stirred tank reactor (CSTR), a plug-flow reactor,a continuous loop reactor, and combinations thereof.

Once complete, the polymerization reaction may be stopped by physicallyseparating the liquid reaction medium from the solid catalyst. In oneembodiment depicted in FIG. 1, the reaction mixture withdrawn frompolymerization reactor 12 via conduit 114 can pass through a catalystfilter 20, wherein the resin solution, which includes the polystyreneproduct, unreacted monomer, various reaction by-products, and solvent,can be separated from the solid acid catalyst. As shown in FIG. 1, theliquid-phase resin solution can be routed via conduit 118 to aseparation/purification zone, while the solid acid catalyst removed fromcatalyst filter 20 via conduit 116 can be optionally recycled topolymerization reactor 12 for reuse via conduit 116a. In someembodiments, at least a portion of the separated catalyst may be asingle-use catalyst and at least some of the catalyst may be discarded,as illustrated by conduit 116b, after removal from catalyst filter 20.

In one embodiment, polystyrene production system 10 can be configured toproduce unhydrogenated polystyrene resin. According to this embodiment,the resin solution removed from catalyst filter 20 can be introducedinto a vacuum separation column 22, wherein the solvent and polymerizateoils (i.e., styrenic dimers, trimers, and oligomers, as well as otherreaction byproducts) can be separated from the polystyrene product viaflash vaporization. The vapor overhead stream, which comprises solventand oils, withdrawn from vacuum separation column 22 can be subsequentlyrouted via conduit 120 to a solvent recovery column 24, wherein thepolymerization solvent can be separated via vacuum flash vaporizationfrom the heavier polymerizate oils. As shown in FIG. 1, at least aportion of the recovered solvent in conduit 122 can be cooled and atleast partially condensed via condenser 26 before being recycled topolymerization reactor 12 for subsequent reuse. The oil-rich liquidstream withdrawn from solvent recovery column 24 can be routed forfurther processing, storage, and/or disposal via conduit 124.

The unhydrogenated polystyrene withdrawn from vacuum separation column22 via conduit 126 can have unique combinations of physical and/orchemical properties, as discussed briefly above. In particular, theunhydrogenated polystyrene produced according to embodiments of thepresent invention can exhibit unexpectedly high softening points and lowz-average molecular weights with relatively narrow polydispersities. Forexample, in one embodiment of the present invention, the unhydrogenatedpolystyrene can have a z-average molecular weight (Mz) of at least about500 dalton, at least about 1,000 dalton, at least about 1,500 daltonand/or not more than about 4,000 dalton, not more than about 3,500dalton, not more than about 3,000 dalton, not more than about 2,500dalton, not more than about 2,300 dalton, or not more than about 2,200dalton, and a polydispersity index, measured as the ratio of numberaverage molecular weight to weight average molecular weight (Mw/Mn) ofat least about 1.1, at least about 1.2, or at least about 1.5 and/or notmore than about 3.5, not more than about 3.0, not more than about 2.5,not more than about 2.0, not more than about 1.9, not more than about1.7, or not more than about 1.65, as determined according to the GPCmethod described in detail in Example 2.

In the same or other embodiments, the unhydrogenated polystyrene canhave a Ring & Ball softening point (ASTM-E28) of at least about 5° C.,at least about 30° C., at least about 50° C., at least about 70° C., atleast about 75° C., at least about 80° C., at least about 85° C., or atleast about 90° C. and/or not more than about 165° C., not more thanabout 150° C., not more than about 130° C., not more than about 125° C.,not more than about 115° C., not more than about 110° C., or not morethan about 105° C. This is in contrast to conventional polystyrene,which typically exhibits a lower softening point and/or widerpolydispersity at the average molecular weight described above.

In some embodiments of the present invention, polymer production system10 illustrated in FIG. 1 can additionally, or alternatively, beconfigured to produce partially or fully hydrogenated polystyrene resin.According to these embodiments, at least a portion, or all, of the resinsolution removed from catalyst filter 20 via conduit 118, can be routedvia conduit 130 to hydrogenation zone 16, as shown in FIG. 1. In oneembodiment wherein the polymerization solvent comprises an aromaticsolvent, the polystyrene resin can be separated from the aromaticsolvent and then re-dissolved in an aliphatic solvent prior to beinghydrogenated (not shown in FIG. 1). In another embodiment wherein thepolymerization solvent comprises an inert or aliphatic solvent, thepolystyrene can be hydrogenated in the same polymerization solvent(i.e., the polymerization solvent can be utilized as a hydrogenationsolvent in hydrogenation zone 16).

Hydrogenation zone 16 can be any system or process capable of at leastpartially hydrogenating the polymer resin in conduit 130. Examples ofsuitable hydrogenation systems and processes are described in U.S. Pat.No. 5,491,214, the disclosure of which is incorporated herein byreference to the extent not inconsistent with the present disclosure. Inone embodiment, the polystyrene can be hydrogenated at a temperature ofat least about 100° C., at least about 150° C., at least about 200° C.and/or not more than about 350° C., not more than about 300° C., or notmore than about 250° C. for a reaction time of at least about 10minutes, at least about 15 minutes, or at least about 20 minutes and/ornot more than about 2 hours, not more than about 1.5 hours, or not morethan about 1 hour. The pressure in hydrogenation zone can be at leastabout 200 psig, at least about 500 psig, or at least about 750 psigand/or not more than about 1,500 psig, not more than about 1,250 psig,or not more than about 1,100 psig and can be applied as the reactionmixture is being heated and/or upon achievement of the desiredhydrogenation temperature. Examples of suitable hydrogenation catalystscan include, but are not limited to, supported nickel, platinum,palladium, copper/zinc, transition metal oxides, and combinationsthereof.

As shown in FIG. 1, the hydrogenated resin solution exitinghydrogenation zone 16 via conduit 132 can subsequently be routed to asolvent recovery column 28, wherein the at least partially hydrogenatedpolystyrene resin product can be separated from the hydrogenationsolvent. In some embodiments, rather than utilizing a separate solventrecovery column 28, vacuum separation column 22 can be operable toprocess at least a portion of the at least partially hydrogenatedpolystyrene resin product withdrawn from hydrogenation zone 16 viaconduit 132. When column 28 is present, the vapor overhead streamwithdrawn via conduit 134 can be subsequently routed to a furthersolvent recovery column 25, wherein the polymerization solvent can beseparated via flash vacuum vaporization from the polymerizate oils. Asshown in FIG. 1, the recovered solvent withdrawn from the overhead offurther recovery column 25 in conduit 137 can be cooled and at leastpartially condensed via passage through condenser 30, before beingrecycled to polymerization reactor 12 for subsequent reuse. The oil-richliquid stream withdrawn from further solvent recovery column 25 can berouted for further processing, storage, and/or disposal via conduit 135.

The resulting at least partially hydrogenated polystyrene resinwithdrawn from hydrogenation zone 16 via conduit 136 can have anaromatic hydrogen content of at least about 2 percent, at least about 5percent, or at least about 7 percent and/or not more than about 25percent, not more than about 20 percent, or not more than about 15percent, as measured by the proton NMR procedure described herein inExample 2. In some embodiments, the polystyrene resin exitinghydrogenation zone 16 may be fully hydrogenated, such that the resin hasan aromatic hydrogen content of not more than about 7 percent, not morethan about 5 percent, or not more than about 2 percent, as measured bythe proton NMR procedure described herein.

In some embodiments, the at least partially hydrogenated polystyreneresin can have a mixed methylcyclohexane aniline point (MMAP) cloudpoint of at least about 60° C., at least about 70° C., or at least about80° C. and/or a diacetone alcohol cloud point (DACP) of at least about30° C., at least about 35° C., or at least about 40° C. and/or not morethan about 75° C., not more than about 70° C., or not more than about65° C. The MMAP and DACP cloud points are determined as described inExample 3, below.

In some embodiment when partially or fully hydrogenated, the polystyreneresin can have a Ring & Ball softening point of at least about 5° C., atleast about 75° C., at least about 80° C., at least about 85° C., atleast about 90° C., at least about 95° C. and/or not more than about150° C., not more than about 140° C., not more than about 135° C., notmore than about 130° C., not more than about 125° C., not more thanabout 120° C. The z-average molecular weight of the at least partiallyhydrogenated polystyrene resin can be at least about 500 dalton, atleast about 750 dalton, at least about 1,000 dalton and/or not more thanabout 4,500 dalton, not more than about 4,000 dalton, not more thanabout 3,500 dalton, or not more than 3,000 dalton, and thepolydispersity (Mw/Mn) can be at least about 1.2 and/or not more thanabout 3.5, not more than about 3.0, not more than about 2.5, not morethan about 2.0, or not more than about 1.9.

In one embodiment of the present invention, one or more of the styrenicresins described above can be used as tackifying resins and/or as partof a tackifying agent in an adhesive composition. In one embodiment, theadhesive composition can be a hot melt adhesive composition selectedfrom the group consisting of hot melt packaging adhesives, hot meltnonwoven adhesives, and hot melt pressure sensitive adhesives. Tables1-3, below, summarize ranges for the major components of exemplaryadhesive compositions prepared according to embodiments of the presentinvention.

TABLE 1 Major Components of Hot Melt Packaging Adhesive CompositionsIntermediate Narrow Component Broad Range Range Range Adhesive Base 25to 80% 30 to 75% 35 to 70% Polymer(s) Tackifying Agent  5 to 55% 10 to50% 15 to 45% Oil optional Wax  1 to 50%  5 to 45% 10 to 40% Antioxidant0 to 5% 0 to 3% 0 to 1%

TABLE 2 Major Components of Hot Melt Nonwoven Adhesive CompositionsIntermediate Narrow Component Broad Range Range Range Adhesive Base 15to 35% 15 to 30% 15 to 25% Polymer(s) Tackifying Agent 10 to 70% 15 to65% 20 to 60% Oil  1 to 30%  2 to 25%  5 to 20% Wax optional Antioxidant0 to 5% 0 to 3% 0 to 1%

TABLE 3 Major Components of Hot Melt Pressure Sensitive AdhesiveCompositions Broad Intermediate Narrow Component Range Range RangeAdhesive Base 20 to 65% 25 to 60% 30 to 55% Polymer(s) Tackifying Agent10 to 60% 15 to 55% 20 to 50% Oil  1 to 20%  2 to 15%  5 to 10% Waxoptional Antioxidant 0 to 5% 0 to 3% 0 to 1%

As shown in Tables 1-3, the hot melt adhesive compositions formulatedaccording to various embodiments of the present invention can compriseone or more adhesive base polymers in combination with a tackifyingagent. The amount of base polymer and tackifying agent can varydepending on the specific type of adhesive formulation. In oneembodiment, the adhesive composition can comprise at least about 15percent, at least about 20 percent, at least about 25 percent, at leastabout 30 percent, or at least about 35 percent and/or not more thanabout 80 percent, not more than about 75 percent, not more than about 70percent, not more than about 65 percent, not more than about 60 percent,not more than about 55 percent, not more than about 35 percent, not morethan about 30 percent, or not more than about 25 percent, by weight, ofone or more adhesive base polymers, based on the total weight of theadhesive composition.

Examples of suitable adhesive base polymers (also referred to aselastomers or adhesive polymer components) can include, but are notlimited to, styrenic block copolymers (SBC), such as,styrene-isoprene-styrene (SIS) copolymers, styrene-butadiene-styrene(SBS) copolymers, styrene-isoprene-butadiene-styrene (SIBS),styrene-ethylene-butylene-styrene (SEBS) copolymers,styrene-ethylene-propylene-styrene (SEPS) copolymers,styrene-butadiene-butylene-styrene (SBBS) copolymers,styrene-ethylene-propylene-styrene (SEPS) copolymers,styrene-ethylene-ethylene-propylene-styrene (SEEPS),styrene-ethylene-propylene (SEP) copolymers, and combinations thereof;metallocene copolymers including polyethylene, polypropylene, and/orpolyolefins; amorphous polyalphaolefins (APAO); olefinic polymers andolefinic block copolymers (OBC); ethyl vinyl acetate (EVA); acrylicblock copolymers (ABCs); polyesters; and combinations of one or more ofthe above-listed polymers. Examples of commercially available basepolymers can include, but are not limited to, those sold under the tradenames ENGAGE, AFFINITY, AFFINITY GA, INFUSE, and VERSIFY (available fromDow Chemical Company, Midland, Mich.); EXACT, LINXAR, VISTAMAXX(available from Exxon Chemical Company, Irving, Tex.); VESTOPLAST(available from Evonik/Degussa, Essen, Germany); REXTAC (available fromRextac/Huntsman, Odessa, Tex.); and NANOSTRENGTH (available from Arkema,King of Prussia, Pa.).

As shown in Tables 1-3, the adhesive composition can include at leastabout 1 percent, at least about 5 percent, at least about 10 percent, atleast about 15 percent, at least about 20 percent and/or not more thanabout 70 percent, not more than about 65 percent, not more than about 60percent, not more than about 55 percent, not more than about 50 percent,not more than about 45 percent, by weight, of the total adhesivecomposition, a tackifying agent. The tackifying agent employed in thehot melt adhesives as described herein can include one or more styrenicresins as described in detail previously. In one embodiment, thetackifying agent can comprise at least about 85 weight percent, at leastabout 90 weight percent, at least about 95 weight percent, or at leastabout 99 weight percent or can consist essentially of or consist of aninventive styrenic resin, while, in other embodiments, the tackifyingagent can include one or more other resins in combination with aninventive styrenic resin. The styrenic resin can be an unhydrogenatedresin, a partially hydrogenated resin, or a fully hydrogenated resin,depending on the specific application or adhesive composition.

When present, the one or more other resins can be selected from thegroup consisting of cycloaliphatic hydrocarbon resins,aromatically-modified cycloaliphatic resins, C5 hydrocarbon resins,C5/C9 hydrocarbon resins, aromatically-modified C5 hydrocarbon resins,C9 hydrocarbon resins, styrene/alpha-methyl styrene copolymer resins,styrene/vinyl toluene copolymer resins, styrene/para-methyl styrenecopolymer resins, styrene/indene copolymer resins, styrene/methyl indenecopolymer resins, styrene/C5 copolymer resins, styrene/C9 copolymerresins, terpene resins, terpene phenolic resins, terpene/styrene resins,rosins, esters of rosins, esters of modified rosins, modified rosins,liquid resins, fully or partially hydrogenated rosins, fully orpartially hydrogenated rosin esters, fully or partially hydrogenatedmodified rosins/rosin esters, fully or partially hydrogenated rosinalcohols, fully or partially hydrogenated C5 resins, fully or partiallyhydrogenated C5/C9 resins, fully or partially hydrogenatedaromatically-modified C5 resins, fully or partially hydrogenated C9resins, fully or partially hydrogenated styrene/alpha-methyl styrenecopolymer resins, fully or partially hydrogenated styrene/vinyl toluenecopolymer resins, fully or partially hydrogenated styrene/para-methylstyrene copolymer resins, fully or partially hydrogenated styrene/indenecopolymer resins, fully or partially hydrogenated styrene/methyl indenecopolymer resins, fully or partially hydrogenated styrene/C5 copolymerresins, fully or partially hydrogenated styrene/C9 copolymer resins,fully or partially hydrogenated C5/cycloaliphatic resins, fully orpartially hydrogenated C5/cycloaliphatic/styrene/C9 resins, fully orpartially hydrogenated cycloaliphatic resins, fully or partiallyhydrogenated aromatically modified cycloaliphatic resins, andcombinations thereof.

In addition to the adhesive base polymer or polymers and the tackifyingagent, adhesive compositions formulated according to various embodimentsof the present invention can comprise one or more additional modifiers,including, for example, oils, waxes, antioxidants, plasticizers,fillers, end block modifiers/polymer reinforcing agents, andcombinations thereof. The types and amounts of the additional modifierscan vary, based on the specific type of adhesive composition beingformulated. For example, in one embodiment wherein the adhesivecomposition comprises a hot melt packaging adhesive, the composition cancomprise a wax in an amount of at least about 1 percent, at least about5 percent, at least about 10 percent and/or not more than about 50percent, not more than about 45 percent, or not more than about 40percent, by weight of the total adhesive composition. Examples ofsuitable waxes can include, but are not limited to, microcrystallinewaxes; metallocene-catalyzed waxes, including polyethylene (mPE) andpolypropylene (mPP) waxes; paraffin (Fischer-Tropsch) waxes; vegetablewaxes; highly-branched, maleated, low molecular weight waxes derivedfrom petroleum; solid oils; and combinations thereof.

In another embodiment wherein the adhesive composition comprises a hotmelt pressure sensitive adhesive or a hot melt nonwoven adhesive, thecomposition can include one or more oils in an amount of at least about1 percent, at least about 2 percent, at least about 5 percent and/or notmore than about 30 percent, not more than about 25 percent, or not morethan about 20 percent, by weight of the total adhesive composition.Examples of suitable oils can include, but are not limited to,naphthenic mineral oil, paraffinic mineral oil, hydrotreated mineraloils, aromatic oils, triglyceride oils, and combinations thereof. Inaddition, the adhesive composition can include one or more extenderoils, such as, for example, liquid paraffin, castor oil, rape seed oil,mineral oil, and combinations thereof.

In addition to waxes and/or oils, the adhesive composition can compriseone or more antioxidants, plasticizers (e.g., dibutyl phthalate, dioxtylphthalate, non-phthalate plasticizers, and/or chlorinated paraffins),fillers (e.g., carbon black, titanium oxide, and/or zinc oxide), endblock modifiers/polymer reinforcing agents, and combinations thereof, aswell as any other additive that would render the final formulationsuitable for a particular application. In some embodiments, one or morestyrenic resins as described above can be added to a polymeric systemincluding at least one polymer material to thereby improve thestability, processability, and/or mechanical and thermal properties ofthe resulting polymer system. In some embodiments wherein the styrenicresin as described above is used as a polymer modification agent, theresin can be utilized an amount of at least about 1 percent, at leastabout 5 percent, or at least about 7 percent and/or not more than about60 percent, not more than about 55 percent, or not more than about 50percent, by weight, of the a mixture of one or more polymers. Thepolymers, which can be present in an amount of at least about 30percent, at least about 35 percent, at least about 40 percent and/or notmore than about 99 percent, not more than about 95 percent, or not morethan about 90 percent, based on the total weight of the composition, canbe selected from the group of adhesive base polymers above. The styrenicresin utilized to enhance the processability of one or more polymericsystems can be unhydrogenated or at least partially hydrogenated, asdescribed in detail above.

Adhesive compositions according to various embodiments of the presentinvention can be prepared using any suitable method. For example, thecomponents of the adhesive composition can be combined in a Sigma blademixer, a Plasticorder, a Brabender mixer, a twin screw extruder, or viaan in-can blend (pint-cans). The resulting adhesive mixture can then beshaped into a desired form by an appropriate technique including, forexample, extrusion, compression molding, calendaring or roll coatingtechniques (e.g., gravure, reverse rolling, etc.). The adhesive can alsobe applied to an appropriate substrate via curtain coating or slot-diecoating or sprayed through a suitable nozzle configuration at anappropriate speed with conventional nonwoven application equipment.

In one embodiment, the adhesive composition as described herein may beapplied to a substrate by melting the blended composition and applying asuitable amount (e.g., from 0.1 to 100 g/m²) of adhesive blend to adesired substrate (e.g., textile fabric, paper, glass, plastic,nonwovens, and/or metal) to thereby form an adhesive article. Examplesof adhesive articles constructed from adhesive compositions according tothe present invention can include, but are not limited to, tapes such aspackaging tape, duct tape, masking tape, invisible tape, electricaltape, gaffer tape, hockey tape, and other specialty tapes; labels suchas paper labels, beverage labels, smart labels, consumer electroniclabels, pharmaceutical labels, labels for graphic arts, and the like;packaging applications including case sealings, book binders, corrugatedbox adhesives, folding carton adhesives, glue sticks, and the like; andnonwoven applications including diaper construction adhesives, diaperelastic attachment adhesives, stretch films, feminine napkin adhesives,adult incontinence product adhesives, disposable bed or pet padadhesives, small nonwoven laminates, and the like.

In addition to adhesive compositions, the styrenic resins describedherein, including unhydrogenated and at least partially hydrogenatedpolystyrene resins, may be useful in other applications. For example, inone embodiment, the polystyrene resins described herein may be used inrubber compositions utilized in one or more components of a tire, suchas, for example, tire treads or sidewalls. In some embodiments, one ormore styrenic resins, as described herein, can be used as a replacementfor various types of oil typically utilized in the tire rubbercompositions, to improve the processability of the rubber compositionand/or to improve the ultimate performance and/or mechanical propertiesof the tire, such as, for example, modulus of elasticity, rollingresistance, wet grip, tensile strength, and the like. Furthermore, otherapplications or uses of the inventive styrenic resins disclosed hereinare contemplated as falling within the scope of the present invention.

EXAMPLES

The following Examples are intended to highlight various aspects ofcertain embodiments of the present invention. It should be understood,however, that these Examples are included merely for purposes ofillustration and are not intended to limit the scope of the invention,unless otherwise specifically indicated.

Example 1 Preparation of Polystyrene Resins

Resin A was prepared as follows. After being separately passed throughfixed beds of alumina to remove polymerization inhibitors and moisture,250 grams each of styrene and Aromatic A-100 solvent (commerciallyavailable from Exxon Mobil Chemical Company, Houston, Tex.) wereintroduced into a 500-mL glass reaction vessel. The vessel was submergedin an external cooling bath of dry ice and isopropyl alcohol to controlthe temperature during polymerization. Under mechanical agitation, thesolution was then cooled to 0° C. and 600 ppm of boron trifluoride, BF₃,was gradually fed into the monomer/solvent blend over a period of 40minutes. After 40 minutes, the resulting reaction mixture was allowed tosoak in the reactor for an additional 30 minutes at 0° C., after whichlime was added to stop the reaction and neutralize any remaining BF₃gas. The resulting polymer solution was then steam stripped to removeresidual solvent and recover the polystyrene resin.

Resin B was prepared according to the same procedure described abovewith respect to Resin A, with the following exceptions. The 250-gramsample of styrene was blended with 250 grams of Recycled HydrogenationSolvent (RHS, commercially available from Eastman Chemical Company),rather than A-100 solvent. In addition, the polymerization and soakingtemperatures were each raised to 30° C.

Resin C was prepared according to the same procedure described abovewith respect to Resin B, except the polymerization and soakingtemperatures were each raised to 70° C.

Resin D was prepared by combining 10 grams of FILTROL F-22 acid claycatalyst (commercially available from BASF, Florham Park, N.J.) with 210grams of A-100 solvent in the reaction vessel. Under agitation, themixture was heated to 65° C. and 290 grams of styrene was incrementallyadded to the reaction vessel over a period of 60 minutes. After all ofthe styrene had been added to the reactor, the reaction mixture wasallowed to soak for an additional 60 minutes at a temperature of 65° C.The spent acid clay catalyst was filtered from the polymer solution andthe resulting polystyrene resin was recovered as discussed above withrespect to Resin A.

Resin E was prepared according to the same procedure described abovewith respect to Resin D, except RHS was utilized as the reactionsolvent.

The polymerization conditions described above for each of Resins A-E aresummarized in Table 4, below.

TABLE 4 Key Polymerization Conditions for Polystyrene Resins A-EPolymerization Catalyst Reaction Temperature Sample Solvent Type TypeSequence (° C.) Resin A A-100 BF₃ straight 0 Resin B RHS BF₃ straight 30Resin C RHS BF₃ straight 70 Resin D A-100 F-22 acid clay reverse 65Resin E RHS F-22 acid clay reverse 65

Once recovered, each of Resins A-E were analyzed to determine thefollowing properties: (1) Ring & Ball softening point; (2) mixed anilinecloud point (MMAP); (3) molecular weight; and (4) molecular weightdistribution (polydispersity). The Ring & Ball softening point wasmeasured according to ASTM E-28 “Standard Test Method for SofteningPoint by Ring and Ball Apparatus” (1996) and MMAP was determinedaccording to ASTM D-611 “Standard Test Methods for Aniline Point andMixed Aniline Point of Petroleum Products and Hydrocarbon Solvents”(2007). The number, weight, and z-average molecular weights (Mn, Mw, andMz) reported above were determined via gel permeation chromatography(GPC) with THF as a solvent according to the following procedure: Eachresin was analyzed at ambient temperature in Burdick and JacksonGPC-grade THF stabilized with BHT, at a flow rate of 1 ml/min. Samplesolutions were prepared by dissolving about 50 mg of each resin in 10 mlof THF and adding 10 microliters of toluene thereto as a flow-ratemarker. An autosampler was used to inject 50 microliters of eachsolution onto a Polymer Laboratories PLgeI™ column set consisting of a 5micrometer Guard, a Mixed-C™ and an Oligopore™ column in series. Theeluting polymer was detected by differential refractometry, with thedetector cell held at 30° C. The detector signal was recorded by aPolymer Laboratories Caliber™ data acquisition system, and thechromatograms were integrated with software developed at EastmanChemical Company. A calibration curve was determined with a set ofeighteen nearly monodisperse polystyrene standards with molecular weightfrom 266 to 3,200,000 g/mole and 1-phenylhexane at 162 g/mole. Themolecular weight distributions and averages were reported either asequivalent polystyrene values or as true molecular weights calculated bymeans of a universal calibration procedure with the followingparameters:

K_(PS)=0.0128 a_(PS)=0.712

K_(CE)=0.00757 a_(CE)=0.842

The results of the above-listed analyses for each of Resins A-E aresummarized in Table 5, below.

TABLE 5 Summary of Results for Analyses of Resins A-E Softening MMAP GPCMolecular Weights Sample Point (° C.) (° C.) Mn Mw Mz Mw/Mn Resin A 90.16 882 1990 3726 2.26 Resin B 130.3 15 3007 12,663 27,849 4.21 Resin C122.7 13 2385 7997 15,325 3.35 Resin D 48.6 −1 425 641 988 1.51 Resin E90.3 4 880 1722 2893 1.96

As shown in Table 5, Resin E was the only polystyrene resin to exhibit arelatively high softening point (e.g., above 70° C.), while stillmaintaining a relatively low z-average molecular weight (e.g., not morethan 3,000 dalton) and a relatively narrow polydispersity (e.g., notmore than 2.0).

Example 2 Preparation of Hydrogenated Styrene Resins

Two samples a polystyrene resin prepared as described in Example 1,above, with respect to Resin E, were hydrogenated under differentconditions in a 1-L hydrogenation autoclave. During the first trial, asample of the polystyrene resin was combined with 1.25 grams of Ni-5256Pnickel hydrogenation catalyst (commercially available from BASF inFlorham Park, N.J.) in RHS and 500 grams of solution were heated in theautoclave to a hydrogenation temperature of 245° C., under nitrogen.Once the desired temperature was achieved, hydrogen was fed into thereactor was increased to 900 psig and held constant as the reactionmixture was mechanically agitated for 25 minutes. At the end ofhydrogenation, the pressure was released and the polymer solution wasallowed to cool to 100° C. before being removed from the autoclave. Thespent catalyst was filtered from the polymer solution and the resultinghydrogenated resin (Hydrogenated Resin F) was steam stripped to removeresidual solvent.

The second trial was conducted in an analogous manner to the first run,except the autoclave contents were heated to the 245° C. hydrogenationtemperature under 900 psig of hydrogen. The resulting hydrogenated resin(Hydrogenated Resin G) was recovered in a similar manner as describedpreviously.

Once recovered, the following properties were determined for each ofHydrogenated Resins F and G: (1) Ring & Ball softening point; (2) mixedaniline cloud point (MMAP); (3) DACP cloud point; (4) molecular weight;(5) molecular weight distribution (polydispersity); and (6)aromatic/aliphatic hydrogen content. The softening point, MMAP,molecular weights, and molecular weight distribution were determined asdescribed above in Example 1. The DACP cloud point was determinedaccording to ASTM D-5773 “Standard Test Method for Cloud Point ofPetroleum Products (Constant Cooling Rate Method)” (2010), and thearomatic/aliphatic content was determined using nuclear magneticresonance (NMR), as described in detail below.

To the aromatic hydrogen content of each hydrogenated polystyrene resin,the ratio of the integration area of aromatic hydrogen relative to thetotal integration area of hydrogen on the resin's NMR spectrum wasdetermined via NMR analysis. The NMR analysis was performed using a JEOL600 MHz Eclipse NMR system with a pulse interval of 15 seconds,acquisition time of 3.6 seconds, pulse angle of 90°, X resolution of0.27 Hz, and number of scans set at 16. The resin NMR samples wereprepared by dissolving a known amount of each of Hydrogenated Resins Fand G in methylene chloride-d2. The total integration value wasnormalized to 100. The results were reported in area percent.

The results of the above-listed analyses for each of Hydrogenated ResinsF and G are summarized in Table 6, below.

TABLE 6 Summary of Analysis of Hydrogenated Polystyrene Resins F and GSoftening GPC Molecular Weights NMR (%) Point DACP MMAP Mw/ AliphaticAromatic Sample (° C.) (° C.) (° C.) Mn Mw Mz Mn Hydrogen HydrogenHydrogenated 91 37 68 764 1297 2145 1.69 91.2 8.6 Resin F Hydrogenated96 55 88 742 1250 2061 1.69 96.5 3.4 Resin G

Subsequent analysis demonstrated the particular compatibility ofHydrogenated Resin F in a hot melt nonwoven adhesive compositioncomprising a blend of SBS copolymers, while Hydrogenated Resin Gexhibited good compatibility with a blend of metallocene polyolefin basepolymers in a hot melt packaging adhesive composition. Additional dataregarding adhesive compositions employing polystyrene resins accordingto embodiments of the present invention will be provided shortly insubsequent Examples.

Example 3 Analysis of Various Tackifying Resins for Use in Hot MeltAdhesive Compositions

Common properties of several different types of tackifying resinssuitable for use in hot melt adhesive compositions were tested andcompared. A list of the tackifiers analyzed is provided in Table 7,below. As shown in Table 7, the comparative tackifying resins analyzedincluded hydrogenated C9 resins (Tackifiers A and B), hydrogenatedpetroleum resins (Tackifiers E, F, G, and H), and hydrogenatedpolystyrene resins prepared in a manner similar to that described withrespect to Resin A in Example 1 (Tackifiers C and D).

The inventive tackifying resins analyzed included both partially(Tackifiers 1 and 2) and fully (Tackifiers 3 and 4) hydrogenatedpolystyrene resins produced via the method described with respect toResin E in Example 1. In particular, Inventive Tackifiers 1-4 wereprepared via reverse addition of styrene to an acid-clay catalyst in thepresence of RHS solvent at polymerization temperatures of 60° C.(Tackifiers 1 and 3) and 55° C. (Tackifiers 2 and 4). The Ring & Ballsoftening point of the base (non-hydrogenated) polystyrene resins rangedfrom 80° C. (Tackifiers 1 and 3) to 85° C. (Tackifiers 2 and 4).

TABLE 7 Summary of Tackifying Resins Analyzed Tackifier Type DescriptionA Comparative Hydrogenated C9 Resin¹ B Comparative Hydrogenated C9Resin² C Comparative Hydrogenated Polystyrene Resin D ComparativeHydrogenated Polystyrene Resin E Comparative Hydrogenated PetroleumResin³ F Comparative Hydrogenated Petroleum Resin⁴ G ComparativeHydrogenated Petroleum Resin⁵ H Comparative Hydrogenated PetroleumResin⁶ 1 Inventive Hydrogenated Polystyrene Resin 2 InventiveHydrogenated Polystyrene Resin 3 Inventive Hydrogenated PolystyreneResin 4 Inventive Hydrogenated Polystyrene Resin Notes: ¹Commerciallyavailable from Eastman Chemical Company as REGALITE S5100. ²Commerciallyavailable from Eastman Chemical Company as REGALITE R7100. ³Commerciallyavailable from Eastman Chemical Company as EASTOTAC H100W. ⁴Commerciallyavailable from Exxon Mobil Chemical Company as ESCOREZ 5600.⁵Commercially available from Eastman Chemical Company as EASTOTAC H130W.⁶Commercially available from Exxon Mobil Chemical Company as ESCOREZ5637.

The Ring & Ball softening point, MMAP, DACP, molecular weights,polydispersity, NMR aliphatic/aromatic/olefinic content, and Gardnercolor were measured for each of the tackifying resins listed in Table 7.All properties were measured as previously discussed in Examples 1 and2, above, and Gardner Color was measured using a Hellige colorcomparator with Gardner varnish color Scales No. C620C-44 Range 1-9 and9-18 according to ASTM D-6166 “Standard Test Method for Color of NavalStores and Related Products (Instrumental Determination of GardnerColor)” (2008). The results of the above-listed analyses for each ofcomparative Tackifiers A-H and inventive Tackifiers 1-4 are summarizedin Table 8, below.

TABLE 8 Results of Property Analyses for Tackifying Resins R&B Aromatic/GPC Molecular Weight Softening MMAP DACP Gardner Aliphatic/ Mw/Tackifier Point (° C.) (° C.) (° C.) Color Olefinic (%) Mz Mn Mw Mn A100 57 18 <1 — 1400 600 900 1.50 (neat) B 102 62 20 <1 — 1500 600 9001.50 (neat) C 100.1 53 15 <1 82.4/17.4/0.2 3959 958 2127 2.22 (neat) D120 85 67 <1 95.2/4.6/0.2 3917 891 1820 2.04 (neat) E 100 81 69 <1 —2150 450 1000 2.22 (neat) F 100 49 31 <2 (50% 90.6/9.0/0.4 950 270 5201.93 toluene) G 130 83 76 <1 99.8/0.2/0.0 2246 464 879 1.89 (neat) H 12756 52 <1 94.4/5.4/0.2 1634 431 666 1.55 (neat) 1 91 68 37 <191.2/8.6/0.2 1692 651 997 1.53 (neat) 2 96 72 — <1 90.9/8.9/0.2 2112 8071325 1.64 (neat) 3 96.3 88 55 <1 96.5/3.4/0.1 1609 621 943 1.52 (neat) 4109 101 69.5 <1 99.7/0.3/0.0 1646 681 1024 1.50 (neat)

Several types of hot melt adhesive compositions that utilize the resinsanalyzed above as tackifying agents are formulated and compared inExamples 4-11, below.

Example 4 Preparation of Hot Melt Adhesive Compositions

Hot melt adhesive compositions, including hot melt nonwoven adhesivesand hot melt packaging adhesives, that employed one or more tackifierslisted in Table 7 were prepared as described below.

Several hot melt nonwoven adhesive compositions were prepared asfollows. An antioxidant was added to an adhesive base polymer, and theresulting mixture was initially masticated in a Plasticorder Brabendermixer using roller blades and sigma blades at a temperature between 125°C. and 177° C. After several minutes, a tackifying agent and an oil wereadded, and the combined mixture was blended for 20 to 45 minutes, untilthe mixer torque plateaued. Tables 10a and 10b, below, summarize thespecific formulations of each of Comparative Nonwoven Adhesives A-C, I,and J and Inventive Nonwoven Adhesives 1 and 5, prepared as describedherein.

Several hot melt packaging adhesives were prepared as follows. Anadhesive base polymer and an antioxidant were combined in a pint-sizedcan. The resulting mixture was agitated with a paddle-type agitatorcontrolled with a variable speed motor and heated with a heating blockto 177° C. under a nitrogen blanket. After the polymer melted, a wax anda tackifier were introduced into the can and the resulting mixture wasagitated for an additional 30 minutes until a homogenous mixture wasobtained. The resulting composition was poured onto a piece ofsilicone-lined cardboard and allowed to cool. Tables 10a and 10b, below,summarize the specific compositions of each of Comparative PackagingAdhesives D-H and K, and Inventive Nonwoven Adhesives 2-4, 6, and 7,prepared as described herein.

TABLE 9a Formulations for Comparative Hot Melt Adhesive Compositions A-KTackifying Comparative Base Polymer(s) Resin/Agent Oil or WaxAntioxidant Adhesive Type Wt % Type Wt % Type Wt % Type⁵ Wt % NonwovenKRATON D1102¹ 19.7 Tackifier A 59.7 CALSOL 19.6 IRGANOX 1.0 Adhesive A5550⁴ 1010 Nonwoven KRATON 19.7 Tackifier B 59.7 CALSOL 19.6 IRGANOX 1.0Adhesive B D1102¹ 5550⁴ 1010 Nonwoven KRATON 19.7 Tackifier C 59.7CALSOL 19.6 IRGANOX 1.0 Adhesive C D1102¹ 5550⁴ 1010 Packaging AFFINITY40.0 Tackifier G 40.0 SASOL H-1³ 20 IRGANOX 0.6 Adhesive D G1950² 1010Packaging AFFINITY 40.0 Tackifier H 40.0 SASOL H-1³ 20 IRGANOX 0.6Adhesive E G1950² 1010 Packaging AFFINITY 40.0 Tackifier E 40.0 SASOLH-1³ 20 IRGANOX 0.6 Adhesive F G1950² 1010 Packaging AFFINITY 40.0Tackifier F 40.0 SASOL H-1³ 20 IRGANOX 0.6 Adhesive G G1950² 1010Packaging AFFINITY 40.0 Tackifier G 40.0 SASOL H-1³ 20 IRGANOX 0.6Adhesive H G1950² 1010 Nonwoven KRATON 19.7 Tackifier A 59.7 CALSOL 19.6IRGANOX 1.0 Adhesive I D1155BO¹ 5550⁴ 1010 Nonwoven KRATON 19.7Tackifier B 59.7 CALSOL 19.6 IRGANOX 1.0 Adhesive J D1155BO¹ 5550⁴ 1010Packaging AFFINITY 40.0 Tackifier C 40.0 SASOL H-1³ 20 IRGANOX 0.6Adhesive K GA1900² 1010 Notes: ¹Commercially available from KratonPolymer, Houston, TX. ²Commercially available from Dow Chemical Company,Midland, MI. ³Commercially available from Sasol Ltd., Johannesburg,South Africa. ⁴Commercially available from Calumet Lubricants,Indianapolis, IN. ⁵Commercially available from BASF, Florham Park, NJ.

TABLE 9b Formulations for Inventive Hot Melt Adhesive Compositions 1-7Tackifying Inventive Base Polymer(s) Resin/Agent Oil or Wax AntioxidantAdhesive Type Wt % Type Wt % Type Wt % Type⁵ Wt % Nonwoven KRATON D1102¹19.7 Tackifier 1 59.7 CALSOL 19.6 Irganox 1010³ 1.0 Adhesive 1 5550⁴Packaging AFFINITY G1950² 40.0 Tackifier 1 40.0 SASOL H-1³ 20 Irganox1010³ 0.6 Adhesive 2 Packaging AFFINITY G1950² 40.0 Tackifier 4 40.0SASOL H-1³ 20 Irganox 1010³ 0.6 Adhesive 3 Packaging AFFINITY G1950²40.0 Tackifier 3 40.0 SASOL H-1³ 20 Irganox 1010³ 0.6 Adhesive 4Nonwoven KRATON 19.7 Tackifier 1 59.7 CALSOL 19.6 Irganox 1010³ 1.0Adhesive 5 D1155BO¹ 5550⁴ Packaging EVATANE 28-420⁶ 33.3 Tackifier 233.3 Paraffin Wax 20 Irganox 1010³ 0.2 Adhesive 6 SASOL H-1³ 13.3Packaging EASTOFLEX 39.9 Tackifier 2 20.0 — — Irganox 1010³ 0.2 Adhesive7 P1023⁷ EASTOFLEX 39.9 P1060⁷ Notes: ¹Commercially available fromKraton Polymer, Houston, TX. ²Commercially available from Dow ChemicalCompany, Midland, MI. ³Commercially available from Sasol Ltd.,Johannesburg, South Africa. ⁴Commercially available from CalumetLubricants, Indianapolis, IN. ⁵Commercially available from BASF, FlorhamPark, NJ. ⁶Commercially available from Arkema Chemical, King of Prussia,PA. ⁷Commercially available from Eastman Chemical Company, Kingsport,TN.

Example 5 Evaluation of Hot Melt Adhesive Compositions Using DynamicMechanical Analysis

Several adhesive compositions prepared in Example 4, above, wereevaluated using Dynamic Mechanical Analysis (DMA). The DMA was performedusing a TA Instruments Ares RDA3 Rheometer in a parallel plate geometryand autostrain mode (maximum strain at 5%). The frequency was 10 Hz andthe heating rate was 6° C./min. Rheological curves, illustrating valuesfor G′ and Tan δ (G″/G′) for both the comparative and inventive nonwovenand packaging adhesives, are provided in FIGS. 2 and 3, respectively.

As shown in FIG. 2, it can be concluded that, while exhibiting a lowersoftening temperature than Comparative Adhesives A-C, as evidenced bythe G′ curves at 25° C., Inventive Adhesive 1 maintains comparable, oreven superior adhesive tack, as evidenced by comparison of therespective Tan δ curves. Thus, it can be concluded that utilizing aninventive hydrogenated polystyrene resin as a tackifying agent resultsin an optimized adhesive blend having both a low application temperatureand sufficient adhesive strength.

Similarly, as shown in FIG. 3, Inventive Adhesives 2-4 also exhibitlower softening temperatures, as evidenced by comparison of the G′curves at 25° C., while maintaining comparable, or even superior,adhesive tack, as evidenced by comparison of the respective Tan δcurves. Further, as evidenced by the single Tg (e.g., maximum peak ofthe G′ curve) for each of Inventive Adhesives 2-4, the components ofthese inventive blends are suitably compatible with each other.

Typically, the difference between the softening point (e.g., the minimumpoint on the G′ curve) and the Tg for each adhesive can be correlated tothe ‘open time’ of the adhesive during its application to a substrate.As shown in FIG. 3, the open times of the Inventive Adhesives 2-4 aresubstantially larger than those of Comparative Adhesives D-H, indicatingthe inventive resins have a longer ‘window’ of application. This,coupled with the low softening point relative to the softening points ofComparative Adhesives D-H, indicate the higher formulation latitude(flexibility) of the Inventive Adhesives 2-4, which, as evidenced by theTan δ curves, still perform as well, if not better than, similarlyproduced Comparative Adhesives D-H.

Example 6 Evaluation of Thermal Stability of Hot Melt AdhesiveCompositions

The thermal stability of each of Comparative Adhesives A-H and InventiveAdhesives 1-4 was analyzed by comparing viscosity curves generatedbefore and after each composition was thermally aged. The initialviscosity curves were generated for each newly formulated sample ofComparative Nonwoven Adhesives A-C and Inventive Nonwoven Adhesive 1using a Brookfield viscometer (DV II, spindle #27) over a range oftemperatures between 130° C. and 210° C. Each sample was then aged in aforced air-draft oven at a temperature of 177° C. for 72 hours. A finalviscosity curve for each of these adhesives was then generated in ananalogous manner. For Comparative Packaging Adhesives D-H and InventivePackaging Adhesives 2-4, the initial viscosity curves were generated ina similar manner, but at temperatures of 300° F., 325° F., and 350° F.Each sample was then aged in a forced air-draft oven at a temperature of177° C. for 96 hours before generating the final viscosity curves in ananalogous manner. FIG. 4 illustrates the initial and final viscositycurves for Comparative Nonwoven Adhesive Adhesives A-C and InventiveNonwoven Adhesive 1, while FIG. 5 presents the initial and final curvesfor Comparative Packaging Adhesives D-H and Inventive PackagingAdhesives 2-4.

As shown in FIG. 4, over the temperature range measured, the initialviscosity of Inventive Nonwoven Adhesive 1 changes not more than theviscosities of any of Comparative Nonwoven Adhesives A-C, indicatingthat Inventive Adhesive 1 has greater thermal stability. Further, it canbe concluded that the adhesive application temperature of InventiveNonwoven Adhesive 1 is lower than that of Comparative Nonwoven AdhesivesA-C, as indicated by the lower viscosity of Inventive Adhesive 1 at agiven temperature. Similarly, as shown in FIG. 5, the initialviscosities of Inventive Packaging Adhesives 2-4 change less over themeasured temperature range than the viscosities of any of ComparativePackaging Adhesives D-H, indicating that Inventive Packaging Adhesives2-4 generally have a greater thermal stability. Further, as indicated bylower viscosities at a given temperature, the adhesive applicationtemperatures of Inventive Packaging Adhesives 2-4 is expected to belower than that of Comparative Adhesives D-H, which may be advantageousduring application of these adhesives to a substrate.

Example 7 Adhesion Strength of Hot Melt Packaging Adhesives D-H and 2-4

The adhesive strength of Comparative Packaging Adhesives D-H andInventive Packaging Adhesives 2-4 were tested over a broad temperaturerange. To evaluate adhesive strength, each adhesive was subjected to ashear adhesion failure test (SAFT), as defined in ASTM D-4498 “StandardTest Method for Heat-Fail Temperature in Shear of Hot Melt Adhesives”(2007). In addition, the percent fiber tear for each adhesive wasdetermined by first applying a sample of each adhesive to a piece ofcorrugated cardboard substrate (having a width of 2 inches and a lengthof 2.5 inches and cut such that the ribs ran lengthwise along thesample) and subsequently measuring percent fiber tear. The SAFT resultsand percent fiber tear results for each of Comparative PackagingAdhesives D-H and Inventive Packaging Adhesives 2-4 are provided in FIG.6 and Table 10, respectively.

TABLE 10 Percent Fiber Tear for Packaging Adhesive Compositions D-H and2-4 Fiber Tear (%) Packaging Adhesive 57° C. 23° C. 4° C. −7° C. −18° C.Comparative Packaging 100 100 100 50 <50 Adhesive D ComparativePackaging 100 100 100 50 50 Adhesive E Comparative Packaging 100 100 100100 100 Adhesive F Comparative Packaging 100 100 100 100 100 Adhesive GComparative Packaging <20 40 <20 <20 20 Adhesive H Inventive Packaging100 100 100 100 100 Adhesive 2 Inventive Packaging 100 100 100 100 100Adhesive 3 Inventive Packaging 100 100 100 100 100 Adhesive 4

As shown in Table 10, Inventive Packaging Adhesives 2-4 each exhibitgood adhesion (100%) at both low (−18° C.) and high (57° C.)temperatures, which is not achieved by many of the comparative packagingadhesives. This conclusion is further supported by the data presented inFIG. 6, which demonstrates the comparability of SAFT failuretemperatures for both comparative and inventive packaging adhesives.Thus, it can be concluded that high softening point, low molecularweight hydrogenated polystyrene resins of the present invention canimpart unique and unexpected properties when utilized as tackifyingresins in adhesive compositions.

Example 8 Evaluation of Hot Melt Adhesives I-K and 5-7 with DynamicMechanical Analysis

Each of Comparative Nonwoven Adhesives I and J, Comparative PackagingAdhesive K, Inventive Nonwoven Adhesive 5, and Inventive PackagingAdhesives 6-8, described in Example 4, above, were analyzed via DMA. Inaddition, each adhesive was subjected to viscosity testing using aBrookfield viscometer at either 338° F. or 350° F., as noted. Theresults of these analyses for each of Comparative Adhesives I-K andInventive Adhesives 5-7 are summarized in Table 11, below.

TABLE 11 Properties of Adhesives I-K and Adhesives 5-7 G′ at 25° C.Adhesive Viscosity (dynes/cm² × Tan δ Softening Composition (cp) 10⁶) Tg(° C.) Value Point (° C.) Comparative  2400¹ 2.03 18.38 2.48 70.35Nonwoven Adhesive I Comparative  2300¹ 1.16 20.37 3.40 68.38 NonwovenAdhesive J Inventive  1800¹ 1.01 18.37 3.01 68.35 Nonwoven Adhesive 5Comparative 1402 579.9 −29.45 0.13 90.39 Packaging Adhesive K Inventive1100 588.9 −11.58 0.21 77.0 Packaging Adhesive 6 Inventive  540 941.7−13.49 0.18 68.4 Packaging Adhesive 7 Inventive 5825 16.49 −3.62 1.10140.3 Packaging Adhesive 8 Notes: ¹Measured at 338° F. All othersmeasured at 350° F.

As illustrated in Table 11, Inventive Packaging Adhesives 5-8, whichutilize low molecular weight, high softening point hydrogenatedpolystyrene resins as tackifying agents, exhibit comparable, or evenbetter, adhesive performance, while still retaining desired stability,as compared to conventional adhesive compositions.

Example 9 Preparation of Adhesive Master Batch Formulations

Six adhesive master batches were prepared by combining one or moreadhesive base polymers with an oil. Specific formulations of each ofadhesive Master Batches (MB) 1-6 are summarized in Table 12, below.

TABLE 12 Compositions of Adhesive Master Batches 1-6 Master Base BatchPolymer 1 Base Polymer 2 Oil (MB) Type¹ Wt % Type¹ Wt % Type Wt % MB 1KRATON 87.0 — — CALSOL 13.0 D1161 5550² MB 2 KRATON 60.9 KRATON 26.1CALSOL 13.0 D1161 D1118 5550² MB 3 KRATON 90.9 — — CALSOL 9.1 D11715550² MB 4 KRATON 33.3 KRATON 50.0 SHELLFLEX 16.7 D1118 D1171 371³ MB 5KRATON 83.3 — — SHELLFLEX 16.7 G1652 371³ MB 6 KRATON 71.4 — — KAYDOL⁴28.6 D1165 Notes: ¹Commercially available from Kraton Polymers, Houston,TX. ²Commercially available from Calumet Lubricants, Indianapolis, IN.³Commercially available from Shell Chemicals, Houston, TX. ⁴Commerciallyavailable from Amoco Chemical, Mahwah, NJ.

Master Batches 1-6 were then utilized to prepare several adhesivecompositions, as described below in Examples 10 and 11.

Example 10 Preparation Hot Melt Adhesives Prepared from Adhesive MasterBatches

Several hot melt adhesive compositions, including nonwoven and pressuresensitive adhesives, were formulated using Master Batches 1-6, describedin Example 9, above. The components of each adhesive were combined in aPlasticorder Brabender mixer and the adhesives were prepared asdescribed in Example 4, above. If needed, a second mixing pass wascarried out in a one-pint unlined paint can equipped with a mechanicalstirrer and a heating block set at 150° C. in order to ensure propermixing of each adhesive. Specific formulations of each of InventiveNonwoven Adhesives 8-10, Comparative Pressure Sensitive Adhesive K, andInventive Pressure Sensitive Adhesives 11-19 are summarized in Table 13,below.

TABLE 13 Comparative and Inventive Hot Melt Adhesive FormulationsPrepared with Master Batches 1-6 Master Tackifying Batch Polymer(s)Resin/Agent Oil or Wax Antioxidant Adhesive Composition # Wt % Type Wt %Type Wt % Type Wt % Type¹² Wt % Comparative Pressure — — KRATON 43.1Tackifier I³ 49.6 CALSOL 6.5 IRGANOX 0.9 Sensitive Adhesive K 1161¹5550⁹ 1010 Inventive Nonwoven 5 21.7 — — Tackifier 1 65.1 SHELLFLEX 13.0IRGANOX 0.2 Adhesive 8 371¹⁰ 1010 Inventive Nonwoven 5 17.4 EASTOFLEX13.0 Tackifier 2 43.4 SHELLFLEX 13.0 IRGANOX 0.2 Adhesive 9 P1023²Tackifier J⁴ 13.0 371¹⁰ 1010 Inventive Nonwoven 6 28.5 — — Tackifier 234.1 KAYDOL¹¹ 2.9 IRGANOX 0.1 Adhesive 10 Tackifier K⁵ 8.6 1010Tackifier L⁶ 28.5 Inventive Pressure 1 46.4 — — Tackifier 2 53.4 — —IRGANOX 0.2 Sensitive Adhesive 11 1010 Inventive Pressure 1 46.4 — —Tackifier 2 30.2 — — IRGANOX 0.2 Sensitive Adhesive 12 Tackifier L⁶ 23.21010 Inventive Pressure 1 36.3 — — Tackifier 2 50.8 CALSOL 12.7 IRGANOX0.2 Sensitive Adhesive 13 5550⁹ 1010 Inventive Pressure 2 46.4 — —Tackifier 2 30.2 — — IRGANOX 0.2 Sensitive Adhesive 14 Tackifier M⁷ 23.21010 Inventive Pressure 2 46.4 — — Tackifier 2 30.2 — — IRGANOX 0.2Sensitive Adhesive 15 Tackifier N⁸ 23.2 1010 Inventive Pressure 3 43.4 —— Tackifier 2 56.4 — — IRGANOX 0.2 Sensitive Adhesive 16 1010 InventivePressure — — Eastoflex 64.1 Tackifier 2 32.1 CALSOL 3.2 IRGANOX 0.2Sensitive Adhesive 17 1060² 5550⁹ 1010 Inventive Pressure 4 45.4 — —Tackifier 2 54.4 — — IRGANOX 0.2 Sensitive Adhesive 18 1010 InventivePressure 1 37.0 — — Tackifier 2 25.9 CALSOL 11.1 IRGANOX 0.2 SensitiveAdhesive 19 Tackifier L⁶ 25.9 5550⁹ 1010 Notes: ¹Commercially availablefrom Kraton Polymer, Houston, TX. ²Commercially available from EastmanChemical Company, Kingsport, TN. ³Commercially available from EastmanChemical Company, Kingsport, TN as REGALREZ 1094. ⁴Commerciallyavailable from Eastman Chemical Company, Kingsport, TN as FORAL-85 E.⁵Commercially available from Eastman Chemical Company, Kingsport, TN asENDEX 160. ⁶Commercially available from Eastman Chemical Company,Kingsport, TN as PICCOTAC 1095. ⁷Commercially available from EastmanChemical Company, Kingsport, TN as PICCOTAC 8095. ⁸Commerciallyavailable from Eastman Chemical Company, Kingsport, TN as PERMALYN 3100.⁹Commercially available from Calumet Lubricants, Indianapolis, IN.¹⁰Commercially available from Shell Chemicals, Houston, TX.¹¹Commercially available from Amoco Chemical, Mahwah, NJ. ¹²Commerciallyavailable from BASF, Florham Park, NJ.

Example 11 Analysis of Hot Melt Adhesives Prepared from Adhesive MasterBatches

Both viscosity and DMA analyses were performed on Inventive NonwovenAdhesives 8-10, Comparative Pressure Sensitive Adhesive K, and InventivePressure Sensitive Adhesives 11-19 summarized in Table 13, above. Theresults of these analyses for each adhesive are summarized in Table 14,below.

TABLE 14 Properties of Hot Melt Adhesives Prepared from Master BatchesViscos- G′ at 25° C. Softening ity (dynes/ Tg Tan δ Point AdhesiveComposition (cp) cm² × 10⁶) (° C.) Value (° C.) Comparative Pressure —1.10 4.37 2.11 70.4 Sensitive Adhesive K Inventive Nonwoven 1800 65.8834.34 2.88 72.4 Adhesive 8 Inventive Nonwoven 1700 3.83 20.39 2.25 112.3Adhesive 9 Inventive Nonwoven 5200 14.43 32.35 5.32 70.4 Adhesive 10Inventive Pressure 61,900 1.37 16.38 2.57 94.4 Sensitive Adhesive 11Inventive Pressure 70,600 1.32 4.39 1.26 108.4 Sensitive Adhesive 12Inventive Pressure 17,900 0.56 2.40 3.11 86.3 Sensitive Adhesive 13Inventive Pressure 58,100 1.05 14.40 2.53 102.4 Sensitive Adhesive 14Inventive Pressure 41,300 1.06 12.38 1.58 94.4 Sensitive Adhesive 15Inventive Pressure 39,600 1.46 12.37 2.49 90.4 Sensitive Adhesive 16Inventive Pressure 4,600 2.96 0.39 1.67 — Sensitive Adhesive 17Inventive Pressure 28,700 1.16 10.36 2.24 94.35 Sensitive Adhesive 18Inventive Pressure 18,600 0.53 2.88 3.11 96.4 Sensitive Adhesive 19

As shown in Table 14, Inventive Pressure Sensitive Adhesives 11-19exhibit good adhesive tack, as indicated by the high Tan δ values, whilestill maintaining a relatively low application temperature and goodshear adhesion, as evidenced by the respective values of G′ at 25° C.

Example 12 Hydrogenated Polystyrene Resins as Polymer System Modifiers

Several modified polymer systems were prepared by combining an amount ofinventive Tackifier 2, prepared as described in Example 3 above, with asystem of base polymers and an antioxidant (commercially available asIRGANOX 1010 from BASF, Florham Park, N.J.). Specific formulations ofeach of Modified Polymer Systems 1-5 are provided in Table 15, below.

TABLE 15 Compositions of Polymer System Modifiers utilizing InventiveResin Master Modifier Batch Base Polymer(s) Tackifier 2 AntioxidantSystem # Wt % Type Wt % Wt % Wt % Modified Polymer 5 24.9 EASTOFLEX 24.949.8 0.2 System 1 E1060² Modified Polymer 5 24.9 AFFINITY 24.9 49.8 0.2System 2 GA1950¹ Modified Polymer 5 24.9 INFUSE 9507¹ 24.9 49.8 0.2System 3 Modified Polymer 5 49.8 — — 49.8 0.2 System 4 Modified Polymer— — AP005 (PCCE)² 49.8 49.8 0.2 System 5 Notes: ¹Commercially availablefrom Dow Chemical Company, Midland, MI. ²Commercially available fromEastman Chemical Company, Kingsport, TN.

Upon formulation, a DMA analysis was conducted on each of ModifiedPolymer Systems 1-5 and the results are summarized in Table 16, below.

TABLE 16 Results of Analysis of Modified Polymer Systems 1-5 G′ at 25°C. Tan δ Softening Modifier System (dynes/cm² × 10⁶) Tg (° C.) ValuePoint (° C.) Modified Polymer 9.62 18.37 1.13 104.3 System 1 ModifiedPolymer 32.97 16.35 0.60 100.4 System 2 Modified Polymer 44.77 18.320.41 108.3 System 3 Modified Polymer 26.20 24.35 0.71 102.4 System 4Modified Polymer 71.06 −43.53 0.54 192.3 System 5

As shown in Table 16, single Tg values exhibited by each ModifiedPolymer System illustrate the compatibility of the inventive tackifierwith the base polymers of each system. Further, the softening point ofeach Modified Polymer System is lower than the individual softeningpoints of each of the base polymers, indicating improved (i.e., lowertemperature) processability for each system.

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary one embodiment, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

We claim:
 1. A process for producing a polystyrene homopolymer resin,said process comprising: (a) combining at least a solid acid catalyst,an inert solvent, and styrene to thereby form a reaction mixture; and(b) polymerizing at least a portion of said styrene in said reactionmixture to thereby produce said polystyrene homopolymer resin having aRing & Ball softening point of at least 85° C. and not more than 110°C., a z-average molecular weight (Mz) from about 500 dalton to about3,000 dalton, and a polydispersity index from about 1.1 to not more than1.7, wherein said inert solvent has an aromatic hydrogen content of notmore than 10 percent, as measured by proton NMR; and wherein saidpolystyrene homopolymer resin comprises styrenic moieties having notmore than 5 weight percent of end-group moieties other than styrenicmoieties.
 2. The process of claim 1, wherein said inert solvent has anaromatic hydrogen content of not more than 5 percent, wherein said inertsolvent comprises one or more cycloaliphatic hydrocarbon compounds. 3.The process of claim 1, wherein said weight ratio of said inert solventto said styrene in said reaction mixture is at least 30:70.
 4. Theprocess of claim 1, wherein during said polymerizing of step (b), thetemperature of said reaction mixture changes by not more than 5° C.,wherein said average reaction temperature is at least 50° C.
 5. Theprocess of claim 1, wherein said polymerizing of step (b) is carried outat a reaction temperature of at least 40° C. and not more than 105° C.6. The process of claim 1, wherein said combining of step (a) includesintroducing said styrene into a pre-mixed slurry of said solid acidcatalyst and said inert solvent to thereby form said reaction mixture.7. The process of claim 1, wherein said reaction mixture comprises atleast 3 weight percent and not more than 10 weight percent of said solidacid catalyst, based on the total weight of said styrene in saidreaction mixture, wherein the moisture content of said solid acidcatalyst is at least 1 weight percent and not more than 8 weightpercent, based on the total weight of said solid acid catalyst.
 8. Theprocess of claim 1, further comprising, subsequent to said polymerizingof step (b), separating at least a portion of said polystyrene polymerfrom said reaction mixture to thereby provide a polystyrene product anda separated reaction mixture and recycling at least a portion of saidseparated reaction mixture for use in said combining of step (a).
 9. Theprocess of claim 1, further comprising, at least partially hydrogenatingat least a portion of said polystyrene homopolymer resin subsequent tosaid polymerizing of step (b) to thereby provide an at least partiallyhydrogenated polystyrene polymer having an aromatic hydrogen content ofnot more than about 15 percent, as measured by proton NMR.
 10. Theprocess of claim 9, further comprising, utilizing at least a portion ofsaid at least partially hydrogenated polystyrene polymer in an adhesivecomposition selected from the group consisting of hot melt pressuresensitive adhesives, hot melt nonwoven adhesives, and hot melt packagingadhesives.
 11. The process of claim 1, wherein said solvent is an inertsolvent having a proton NMR aromaticity of not more than 10 percent,wherein said inert solvent comprises tetramethylcyclohexane,trimethylcyclohexane, hexane, cyclohexane, heptanes, mineral spirits, orcombinations thereof.
 12. The process of claim 11, wherein the weightratio of said inert solvent to said one or more monomers in saidreaction mixture is at least 30:70.
 13. The process of claim 1, whereinsaid polymerizing of step (b) is carried out at an average reactiontemperature of at least 40° C. and not more than 105° C. and saidreaction temperature changes by not more than 5° C. during saidpolymerizing of step (b).
 14. The process of claim 1, furthercomprising, at least partially hydrogenating at least a portion of saidpolystyrene homopolymer resin subsequent to said polymerizing of step(b) to thereby provide an at least partially hydrogenated polystyrenepolymer having an aromatic hydrogen content of at least about 2 percent,as measured by proton NMR.